Yak bone. Tibetans in the western Sichuan Plateau carved scriptures on yak skulls as sacrifices, and people also regarded yak bones as a unique ornament. Tibetan women like to wear all kinds of decorations around their necks, including necklaces made of different ancient seashells (called "silk"), necklaces made of colored beads, seashells and turquoise, and decorations of different lengths made of bones, jewels and wax beads.